This application claims benefit of Japanese Application No. 2000-25566 filed in Japan on Feb. 2, 2000, the content of which are incorporated by this reference.
1. Field of the Invention
The present invention relates to an improved endoscope capable of being successfully subjected to autoclave sterilization (high-pressure, high-temperature steam sterilization).
2. Description of the Related Art
At present, endoscopes are widely employed. An endoscope can observe a deep region and the like within a body cavity or the like by inserting an elongate insertion portion into the body cavity, and can conduct a therapeutic treatment by using a treatment tool at need. To prevent infectious disease and the like, it is essential to disinfect and sterilize a medical endoscope of this type.
Conventional disinfection and sterilization treatments have mainly been a gaseous sterilization treatment employing sterilization gas such as ethylene oxide gas and a sterilization treatment with a disinfectant. However, as is well known, sterilization gas is deadly poison and every country increasingly restricts use of the sterilization gas so as to prevent environmental pollution.
Further, aeration is carried out in the course of the gas sterilization treatment stated above. This aeration is intended to remove gas adhering to a sterilized equipment after sterilization. Since the aeration takes a lot of time, the sterilized endoscope cannot be disadvantageously used right after the sterilization. Besides, the gas sterilization treatment as stated above disadvantageously requires high running cost.
Meanwhile, the sterilization treatment with a disinfectant has a disadvantage in that the management of the disinfectant is complicated. Further, the sterilization treatment with a disinfectant requires a large cost for the disposal of the used disinfectant.
In these circumstances, therefore, autoclave sterilization (high-pressure, high-temperature steam sterilization) becomes popular as the sterilization of endoscope equipment. The autoclave sterilization (high-pressure, high-temperature steam sterilization) does not follow complicated operation, allows an endoscope to be used soon after the sterilization and requires low running cost.
Typical conditions for the autoclave sterilization are specified by the American National Standard Institute authorized, US standard ANSI/AAMI ST37-1992 published by the Medical Equipment Development Association. According to this condition, a sterilization step for pre-vacuum type sterilization is conducted at 132xc2x0 C. for 4 minutes, and a sterilization step for gravity type sterilization is conducted at 132xc2x0 C. for 10 minutes.
However, high-pressure, high-temperature steam used for the autoclave sterilization has a property of transmitting a polymeric material such as rubber or plastic which constitutes the endoscope equipment, an adhesive agent and the like. Epoxy resin which has been conventionally, normally used as an adhesive agent, in particular, tends to be deteriorated by high-temperature steam and to peel off. Due to this, if autoclave sterilization is conducted, there is fear that steam easily enters the interior of a lens system.
Furthermore, due to the difference in the coefficient of thermal expansion among materials, a stress is applied to respective members constituting the endoscope equipment. This stress causes the adhesive agent used between the respective members to peel off, with the result that steam may possibly enter the interior of the lens system.
According to the conventional endoscope, therefore, if the endoscope is placed into an autoclave sterilization apparatus and subjected to autoclave sterilization, steam enters even the interior of the structure which has been constituted watertight by an ordinary method using an O ring, an adhesive agent or the like.
Moreover, a vacuum step is conducted prior to a sterilization step in the course of the autoclave sterilization. In this connection, there is proposed a method of placing an endoscope into an autoclave sterilization apparatus while the interior and exterior of the apparatus are kept continuous to each other at the time of this vacuum step prior to the sterilization step. This method is intended to prevent an envelope tube used at the bent portion of the insertion portion of the endoscope from rupturing. According to this method, steam for the autoclave sterilization is positively infiltrated into the endoscope.
If an endoscope having an object lens fixed thereto by an adhesive agent is subjected to autoclave sterilization, for example, steam is infiltrated into the interior of an object optical system through the adhesive agent.
If an endoscope having an object lens fixed thereto by an adhesive agent is placed into an autoclave sterilization apparatus and subjected to autoclave sterilization, steam is infiltrated even into the interior of the object optical system through the adhesive agent. As a result, if the endoscope is taken out from the autoclave sterilization apparatus into a room after the autoclave sterilization and observed from the eyepiece of the endoscope, then the lens becomes clouded up with steam and appears foggy. This fog is gradually cleared off and a normal observation image can be obtained.
Nevertheless, while the lens is clouded as stated above, the endoscope cannot be used. Due to this, a test using the endoscope makes little progress, which is considerably inconvenient.
Additionally, autoclave sterilization is sometimes repeatedly conducted or continuously conducted for a long time. In this case, the junctions of the object optical system are greatly deteriorated by the high-pressure, high-temperature steam used for the autoclave sterilization. The junction regions of components made of a stainless material constituting the object optical system may possibly peel off.
The above-stated phenomena also occur to an electronic endoscope including a solid-state image pickup device such as a CCD. The electronic endoscope is comprised of an image pickup unit including an object optical system arranged on the image incidence end face of the solid-state image pickup device. The constituent components made of a stainless material of the image pickup unit including the object optical system are coupled to one another by an ordinary adhesive agent.
If the electronic endoscope as stated above is placed into an autoclave sterilization apparatus and subjected to autoclave sterilization, high-pressure, high-temperature steam used for this autoclave sterilization enters the interior of the image pickup unit including the object optical system. Due to this, if an endoscope image picked up by the image pickup unit is displayed on a monitor, a normal image cannot be shown thereon because of the cloud or the like of the object lens within the image pickup unit. Further, if autoclave sterilization is conducted repeatedly or conducted continuously for a long time, the junctions of the respective constituent components of the image pickup unit may possibly peel off.
To solve the above-stated disadvantages, there is proposed an endoscope described in, for example, Japanese Patent Application No. 10-234649 filed previously by the applicant of the present application which endoscope is provided with an airtight unit having optical elements and insulating members airtight coupled to a metal frame by soldering. The airtight unit is capable of preventing the entry of steam from the outside of the endoscope into the optical system.
The above-stated airtight unit includes a solid-state image pickup device such as a CCD and electronic components such as an IC. In the airtight unit, these components are coupled by an adhesive agent at the time of assembling an optical member such as a lens, an image pickup unit and the like.
The above-stated endoscope, however, has a disadvantage in that if the image pickup unit is small in size, heat is transferred to the image pickup device such as a CCD and the electronic components such as an IC during a soldering operation when the image pickup unit is assembled, and the electronic components may be possibly damaged or the adhesive agent may possibly peel off.
It is an object of the present invention to provide an endoscope capable of ensuring airtight coupling and constituting an optical system unit which electronic components and the like are unlikely to be damaged.
It is another object of the present invention to provide an endoscope capable of preventing optical members such as an object lens and a cover glass from being deteriorated by high-pressure, high-temperature steam used for autoclave sterilization, preventing the optical members from becoming clouded up with dew generated by the entry of steam and being subjected to autoclave sterilization repeatedly.
It is yet another object of the present invention to provide an endoscope capable of preventing the formation of dew (or becoming clouded) within a cover glass even if the endoscope is quickly cooled down after the autoclave sterilization.
It is yet another object of the present invention to provide an endoscope capable of easily adjusting a distance (focusing) between a lens group and a solid-state image pickup device and being observed by a clear endoscope image.
It is yet another object of the present invention to provide an endoscope capable of making the outside diameter of the periphery of the lens of an image pickup unit, reducing the outside diameter of an insertion section and easing patients"" burden.
An endoscope according to the present invention comprises an optical system unit having a plurality of units formed by airtight coupling a metal member to at least a part of the surface of a nonmetal member which surface has been metallized by soldering or brazing, and formed integrally by airtight welding the metal members of the plurality of units.
Other characteristics and advantages of the present invention will become fully obvious on reading the following description.